Oscillatory rotary actuators employing radial vanes mounted on a stator and on a shaft are well known. See, for example, U. S. Pat. Nos. 3,128,679, 3,131,610 and 3,215,046 wherein three such devices are described. Also in my co-pending application Ser. No. 06/548,950, filed Nov. 7, 1983, now U.S. Pat. No. 4,495,856, there is described an improved rotary actuator having durable seals and improved thrust bearings for preventing axial movement of the shafts.
In the past the rotors of fluid-operated rotary actuators have been sealed to the heads by O-rings, quad-seals or the like formed of an elastomeric material, such as rubber, and U-shaped resilient sealing gaskets formed of rubber or the like mounted in complimentary grooves in the vanes of the stator and the rotor. This construction had the disadvantage of a relatively short seal life because of the fact that one rubber seal rubbed against the other. It would be desirable, therefore, to replace one of the elastomeric seals with a less abrasive material such, for example, as tetrofluroethylene.